1. Field of the Invention
The present invention relates to optical pickups for use in optical disk apparatuses.
2. Description of the Related Art
Laser diodes have been widely used as laser sources of optical pickups for used in optical disk apparatuses. The laser diodes have many advantages. For example, since the size of each laser diode is small and the power consumption thereof is low, the size of an optical pickup including the laser diode can be minimized.
A laser beam emitted from a laser diode has an elliptical cross-sectional shape (far-field pattern). Consequently, a spot formed by focusing the laser beam through an objective lens is also elliptical. In an optical pickup including such a laser diode, in order to optimize the shape of a laser beam spot to be formed on a track, the laser diode is mounted on the optical pickup such that the optical axis of the laser diode is rotated by a predetermined angle. Consequently, the track is irradiated with a laser beam rotated by the predetermined angle such that a beam spot with an optimum shape is formed on the track.
An integrated optical pickup is proposed as one of optical pickups for use in optical disk apparatuses. The integrated optical pickup includes, for example, a laser diode, a top emission prism, a package which is a molded part, made of ceramic, for sealing the laser diode and the prism, and an integrated optical assembly including a beam splitter, a diffraction grating, and a photodetector such that the integrated optical assembly is mounted on the package. Japanese Unexamined Patent Application Publication No. 2003-248960 discloses such an integrated optical pickup.